Self-aligning clutch bearing assembly

ABSTRACT

A clutch release bearing wherein an annular wear plate is supported on the outer race structure of the bearing for limited displacement relative thereto by means of a resilient annular element. When the bearing is shifted axially of the clutch to uncouple driving and driven clutch members from each other, the wear plate contacts the release levers of the clutch at a location disposed radially displaced either inwardly or outwardly from the bulk of the resilient annular element. The bulk of the resilient annular element is also disposed axially between where it engages the annular wear plate and where it engages the outer race structure. In this way, the wear plate can assume a position wherein it generally uniformly engages all individual release levers of the clutch and with a minimum of relative movement occurring therebetween. Thus, the annular wear plate is considered self-aligning and provides a bearing construction which compensates for both out-of-square and eccentricity conditions which may exist. The annular wear plate may have an annular conical flange for engagement with the clutch release levers for increasing the tractive force between the clutch levers and wear plate which exists during conditions of eccentricity between the axis of the engine flywheel relative to the axis of the transmission input shaft.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention is directed to bearing assemblies generally and inparticular, to those of the type commonly used as clutch releasebearings in automobile friction disc clutches.

Two common problems in the clutch release bearing art are: (1)eccentricity of the bearing axis (transmission input shaft axis)relative to the engine flywheel axis and (2) an out-of-square conditionbetween the clutch release levers and the bearing. "Out-of-square" is afamiliar term used in the art to describe a condition whereby the planedefined by the tip of the clutch release levers or fingers is notparallel to the plane of the bearing face which they engage. The firstproblem results in undue wear between both the bearing face and the tipsof the clutch levers because of the reciprocating motion therebetweenwhich takes place after engagement and prior to the bearing and clutchdisc rotating as one unit. The second problem results in undue wearoccurring on one particular clutch release lever during one particularclutch release. In other words, the entire axial load exerted whiledepressing the clutch, which is generally in the order of 500 pounds, isexerted by one clutch finger, or at any rate, less than all clutchfingers, and when this occurs, in an eccentrically mounted bearingassembly, the amount of wear caused by the reciprocating motion betweenthat particular clutch finger and the bearing face is significantlyincreased over what it would be were it not in the out-of-squarecondition. These two problems are the result of variations in tolerancesarising from currently practiced manufacturing and assembly techniquesfor the complete clutch and transmissions, and it is not consideredeconomically practical to try to further control these variances. Myinvention automatically compensates for these variances.

A description of the invention appears in the ensuing specification,including claims, which is to be taken in conjunction with theaccompanying drawing. The drawing illustrates preferred embodiments ofthe invention in accordance with the best mode presently contemplated incarrying out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view having portions broken awaythrough a conventional automotive type friction disc clutch assemblyhaving a release bearing embodying principles of the present invention;

FIG. 2 is an enlarged longitudinal sectional view through the clutchrelease bearing of FIG. 1 shown by itself;

FIG. 3 is an enlarged fragmentary sectional view showing an additionalembodiment;

FIG. 4 is a view similiar to FIG. 3 showing a still further embodiment;

FIG. 5 is a view similar to FIG. 3 showing a still further embodiment;and

FIG. 6 is a view similar to FIG. 2 illustrating yet another embodimentduring actuation of the clutch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a sectional view of a typical single disc friction clutch 10having a self-aligning clutch release bearing 12 embodying theprinciples of the present invention. Briefly, clutch 10 has a housing 14which encompasses flywheel 16 driven by input shaft 18, typically theengine crankshaft. A backing plate 20 is bolted to flywheel 16 and apressure plate 22 is urged by a plurality of springs 24 (to the left asviewed in FIG. 1) to press a clutch disc 26 against flywheel 16. Disc 26has annular facings 28 and 30 of a friction material on opposite sidesthereof. A hub 32 is affixed to the inner periphery of disc 26 and isdrivingly coupled via splines with an output or transmission shaft 34.When the clutch is in the engaged position shown in the drawing,flywheel 16, plate 20, 22, disc 26, hub 32 and shaft 34 rotate togetherwhen shaft 18 turns. A clutch pedal 36 is pivoted on a stub shaft 38 andan actuating fork 40 is also affixed to shaft 38. When pedal 36 isdepressed, fork 40 shifts clutch release bearing 12 to the left asviewed in FIG. 1. Bearing 12 is mounted on a cylindrical sleeve 42around shaft 34, although it could be mounted on shaft 34 directly if sodesired. When bearing 12 is shifted to the left as viewed in FIG. 1, itengages release levers 44 which are pivoted as at 46 on backing plate20. The opposite ends of levers 44 are arranged to engage bushings 48which are affixed to pressure plate 22. With the release levers 44pivoted by bearing 12, pressure plate 22 is shifted to the right asviewed in FIG. 1, thereby releasing disc 26 from the pressure applyingrelation with flywheel 16. With the exception of bearing 12, clutch 10is of entirely conventional construction and merely illustrative of thetypes to which the present invention is applicable. Details of the novelclutch release bearing according to the present invention are disclosedbest in FIGS. 2-6.

Therefore, turning first to FIG. 2, the clutch release bearing 12comprises an inner race member 50 having a raceway 50r, an outer racemember 52 having a raceway 52r, a plurality of anti-friction bearingelements 54 in the form of spherical balls riding in raceways 50r, 52r,a cage 55 for circumferentially spacing the balls, a retainer 56 and anovel self-aligning structure 58, which structure is composed of anannular wear plate 60, a resilient annular element 62 preferably ofelastomeric type material and an annular collar 64. The components 50,52, 54, 55, 56 are entirely conventional and may be made in accordancewith well-known techniques. Attention is therefore focused on details ofthe novel self-aligning structure 58. It will be observed in FIG. 2 thatcollar 64 has the right-hand end thereof telescoped over the cylindricalouter surface of outer race member 52. This leaves the left-hand freeend of collar 64 projecting axially beyond the end of outer race member52. Wear plate 60 has circular inner and outer peripheries and the outerdiameter thereof is substantially less than the inside diameter ofcollar 64. It will also be observed that wear plate 60 is spaced axiallyfrom the end of outer race member 52. The resilient annular element 62may be considered generally as being somewhat conically shaped tosupport wear plate 60 generally radially inwardly and generally axiallyoutwardly of the free end of collar 64. With this construction it willbe noted that a substantial portion of the bulk of element 62 is locatedaxially intermediate wear plate 60 and outer race member 52.Furthermore, the bearing is arranged such that the bulk of the element62 is disposed radially beyond the point at which the clutch releaselevers 44 contact wear plate 60 when the bearing is shifted to disengagethe clutch. (This will be explained later in connection with FIG. 6.) Byvirtue of this construction, the self-aligning characteristics of thebearing for compensating for the aforementioned eccentricity andout-of-square conditions are greatly enhanced over prior art bearings.It is also preferable to provide in element 62 an annular groove 66 viawhich element 62 can mate with the free end of collar 64 and also anannular groove 68 via which the resilient element can mate with wearplate 60. It is also preferable to provide a portion of the resilientmaterial directly axially between wear plate 60 and the outer racemember 52, and as shown in FIG. 2, this portion is provided with aradially inwardly facing conical surface 70. By constructing andlocating resilient element 62 in such manner relative to the wear plate60, the wear plate 60 is in effect cantilevered and its positionrelative to the plane of the race member 52 is very flexible so that itcan adapt to uneven engagement by out-of-square clutch levers. Element62 may be bonded to wear plate 60 and collar 64 by suitable bondingmeans.

FIGS. 3, 4 and 5 illustrate additional embodiments of the invention andlike numerals are retained to designate like elements. In FIG. 3, theembodiment is identical to that of FIG. 2 insofar as the self-aligningstructure 58 is concerned. However, it will be noted that theconstruction of the bearing elements 150, 152 and 156 is typical of aconventional thrust bearing which is also commonly used for clutchrelease applications.

FIG. 4 is like FIG. 2 except that the embodiment of FIG. 4 has aslightly different self-aligning structure 58a characterized by adifferent resilient element 62a. It will be noted that instead of theconically-shaped surface 70 provided in the embodiment of FIG. 2, thatthe embodiment of FIG. 4 is provided with a V-shaped groove 70a instead.This provides further advantageous and beneficial deflectioncharacteristics.

The embodiment of FIG. 5 is the same as FIG. 2 except that a differentself-aligning structure 58b is provided. Here instead of having collar64 telescoped over the outer periphery of outer race member 52 as inFIG. 2, a smaller diameter collar 64b is fitted into the inner peripheryof outer race member 52. The wear plate 60 is supported from the freeend of collar 64b via a resilient annular element 62b which is lodgedaround collar 64b and against outer race member 52. A groove 68b isprovided which mates with the inner periphery of wear plate 60. Asection of the annular element 62b is disposed directly between wearplate 60 and outer race member 52 and has a radially outwardly facingcone surface 70b.

The embodiment of release bearing shown in FIG. 6 illustrates a furtheraspect of the invention which provides even further advantages. (FIG. 6illustrates the bearing assembly during actuation of the clutch releaselevers 44 and such actuation will be explained in the succeedingparagraph.) In the embodiment of FIG. 6, wear plate 60, instead of beinga flat annular element lying entirely in a plane perpendicular to thebearing axis when the bearing is in the free state (as in the previousembodiments), is provided with an annular conical flange 60a extendingaround the inner periphery thereof. Flange 60a tapers radially inwardlyin the direction facing away from the rest of the bearing. Flange 60acontributes to the self-aligning characteristics of the bearing assemblyby providing in effect a mechanical interlock with the clutch releaselevers 44 when the bearing assembly is shifted axially. A bearing whichincludes flange 60a possesses even better self-aligning characteristicsfor more uniformly operating the release levers during actuation of theclutch and alleviating wear and tear on the bearing and release levers.

The operational advantages of the invention are best highlighted whenconsidering operation of the clutch as illustrated in FIG. 6. (Note thatthe section in FIG. 6 is taken along planes passing through the releaselevers which are arranged circumferentially around the clutch axis.) Theinner ends of levers 44 have balled sections 44a which are positioned tobe contacted by wear plate 60 when bearing assembly 12 is shiftedaxially (to the left as viewed in FIG. 1) to disengage the clutch. Whenneither an out-of-square condition nor an eccentricity condition exists,flange 60 uniformly simultaneously contacts release levers 44 when thebearing is shifted. As the load imposed by release levers is taken bythe bearing, resilient element 62 generally uniformly deforms slightlyas wear plate 60 is displaced slightly toward the outer race member 52.Assuming an eccentric condition exists, because of misalignment of inputand output shafts 18 and 34, the resilient nature of element 62 allowsplate 60 to move about the axis of the bearing, and because of thismovement, the relative movement between plate 60 and the clutch levers44 is reduced. Generally, the type of movement between plate 60 and theaxis of rotation of bearing 52 would be described as oscillatory,whereas the motion between the clutch levers at the plate 60 at themutual point of contact is reciprocatory. Quite obviously the linealextent of this "reciprocation" absent the improvement of my inventionequals the amount of eccentricity between the input and output shaftaxes. The "tractive" force which radially drives plate 60 is generallyequal to the axial force exerted through clutch pedal 36 times thecoefficient of friction between clutch levers and wear plate. In theembodiment of FIG. 6, I have increased the tractive force by provisionof conical flange 60a which provides a radial component of force inaddition to whatever force is provided by the presence of friction.Other means of increasing tractive force can also be provided, such asincreasing the coefficient of friction of wear plate 60 by selection ofmaterial and/or surface finish.

In all embodiments shown, it will be understood that if there exists anout-of-square condition, the loading of clutch levers on the wear platewill be quickly evenly distributed the moment the leading clutch levercontacts the wear plate. This results from the fact that the wear plateis resiliently suspended, which allows it to be forced inwardly at thatparticular point of contact with the leading clutch finger and therebybrings the lagging clutch levers into engagement. This permits theremaining release levers to be engaged by the wear plate before anyappreciable loading occurs between the bearing and the leading clutchlever.

All in all, the present invention provides important improvements inoperational performance over prior art bearings. Furthermore, theinvention can be practiced with maximum economy. As shown in thepreferred embodiments of FIGS. 2-5, the wear plate is a flat annularpiece; hence, it can be blanked and pierced from sheet material and thisis far simpler than more complicated fabrication techniques required byprior art bearings. In FIG. 6, the conical flange 60a can be easilyformed by stamping. The resilient element 62 and collar 64 may also bereadily fabricated and the three elements 60, 62, 64 can be readilyassembled together and mounted on outer race member 52.

It is understood that the foregoing description is that of a preferredembodiment of the invention. Various changes and modifications may bemade without departing from the spirit and scope of the invention asdefined by the appended claims.

What is claimed is:
 1. In a clutch having input and output membersnormally operatively coupled to rotate together about the clutch axisand means for operatively uncoupling said two members comprising aplurality of pivotally mounted release levers on the clutch, saidrelease levers having actuating portions thereof arranged to lieapproximately on a circle which is at least approximately perpendicularto and at least approximately coaxial with the axis of the clutch, aclutch release bearing shiftable axially of the clutch to engage theactuating portions of said release levers and operate said levers so asto operatively uncouple said two members, said clutch release bearingcomprising: an inner race means comprising a raceway; an outer racemeans comprising a raceway; a plurality of anti-friction bearingelements constrained between said two race means and riding in theraceways thereof; annular wear plate means disposed in a planeperpendicular to the axis of said bearing and arranged to engage theactuating portions of said release levers for operating the latter; andmeans for supporting said wear plate means on said outer race meanscomprising an annular axially-extending portion affixed to said outerrace means having a free end and a resilient annular element interposedbetween and affixed to said free end of said annular axially-extendingportion and to said wear plate means; said wear plate means, said outerrace means and said resilient annular element being arranged andconstructed such that the bulk of said resilient annular element isdisposed axially intermediate the location at which it engages said wearplate means and the location at which it engages said annularaxially-extending portion, the bulk of said resilient annular elementbeing radially offset from the point of contact between said wear platemeans and the actuating portions of said release levers.
 2. A clutchrelease bearing as claimed in claim 1 wherein said wear plate means andsaid resilient annular element are arranged such that the bulk of saidresilient annular element is disposed radially inwardly of the point ofcontact between the actuating portions of said release levers and saidwear plate means.
 3. A clutch release bearing as claimed in claim 1wherein said wear plate means and said resilient annular element arearranged such that the bulk of said resilient annular element isdisposed radially outwardly of the point of contact between theactuating portions of said release levers and said wear plate means. 4.A clutch release bearing an claimed in claim 1 wherein said wear platemeans comprises an annular wear plate element having radial inner andouter peripheries and wherein said resilient annular element is affixedto one of said peripheries of said annular wear plate element.
 5. Aclutch release bearing as claimed in claim 4 including a groove in saidresilient annular element mating with said one of said peripheries ofsaid annular wear plate element.
 6. A clutch release bearing as claimedin claim 4 wherein the bulk of said resilient annular element isdisposed radially beyond said one of said peripheries of said annularwear plate element.
 7. A clutch release bearing as claimed in claim 6wherein said resilient annular element is affixed to and has the bulkthereof disposed radially outwardly of the outer periphery of saidannular wear plate element.
 8. A clutch release bearing as claimed inclaim 6 wherein said resilient annular element is affixed to and has thebulk thereof disposed radially inwardly of the inner periphery of saidannular wear plate element.
 9. A clutch release bearing as claimed inclaim 6 wherein said resilient annular element has a section thereofdisposed directly axially between a portion of said annular wear plateelement and said free end of said annular axially-extending portion,said section having a radially facing exposed surface.
 10. A clutchrelease bearing as claimed in claim 9 wherein said radially facingexposed surface of said section of said resilient annular element facesradially inwardly.
 11. A clutch release bearing as claimed in claim 10wherein said radially inwardly facing exposed surface is V-shaped.
 12. Aclutch release bearing as claimed in claim 10 wherein said radiallyinwardly facing exposed surface is conically shaped.
 13. A clutchrelease bearing as claimed in claim 9 wherein said radially facingexposed surface of said section of said resilient annular element facesradially outwardly.
 14. A clutch release bearing as claimed in claim 13wherein said radially outwardly facing exposed surface is conicallyshaped.
 15. A clutch release bearing as claimed in claim 1 wherein saidresilient annular element is formed with a groove which mates with thefree end of said annular axially extending portion.
 16. A clutch releasebearing as claimed in claim 1 wherein said wear plate means comprises anannular wear plate element having radially inner and outer peripheries,said resilient annular element being affixed to one of said peripheriesof said annular wear plate element.
 17. A clutch release bearing asclaimed in claim 16 wherein said one periphery of said annular wearplate element has a diameter different from the diameter of said freeend of said annular axially-extending portion.
 18. A clutch releasebearing as claimed in claim 17 wherein said resilient annular element isaffixed to the outer periphery of said annular wear plate element andthe outer periphery of said annular wear plate element has a diameterwhich is less than the diameter of said free end of said annularaxially-extending portion.
 19. A clutch release bearing as claimed inclaim 17 wherein said resilient annular element is affixed to the innerperiphery of said annular wear plate element and the inner periphery ofsaid annular wear plate element has a diameter exceeding the diameter ofthe free end of said collar.
 20. A clutch release bearing as claimed inclaim 17 wherein said resilient annular element includes a groove matingwith said one periphery of said annular wear plate element and anothergroove mating with the free end of said collar.
 21. A clutch releasebearing as claimed in claim 1 wherein said wear plate means includescamming means thereon interengageable with the clutch release leverssuch that whenever upon shifting of the bearing one of said releaselevers is contacted by said wear plate means before another of saidrelease levers the interengagement of said camming means and said onerelease lever causes said wear plate means to be bodily displacedgenerally radially thereby tending to center said wear plate means withrespect to the release levers.
 22. A clutch release bearing as claimedin claim 21 wherein said camming means comprises an annular conicalflange on said wear plate means.
 23. In a bearing assembly having innerand outer race means and a plurality of anti-friction bearing elementsconstrained between said inner and outer race means, the inventionwherein said outer race means is provided with a free annular axiallyextending portion and an annular wear plate having inner and outerperipheries is disposed in a plane perpendicular to the axis of thebearing assembly and supported from said free annular portion by aresilient annular element so as to permit limited deflection of saidwear plate in a plane perpendicular to the axis of the bearing assemblyand in planes angularly tilted with respect to said axis of the bearingassembly relative to said outer race means and thereby provide thebearing assembly with a self-aligning capability, said resilient annularelement having inner and outer peripheries, one of said peripheries ofsaid resilient annular element being affixed to said free annularaxially extending portion and the other periphery of said resilientannular element being affixed to one of the peripheries of said annularwear plate, the inner and outer peripheries of said resilient annularelement being offset both radially and axially relative to each otherwith the bulk of said resilient annular element being disposedtherebetween.
 24. The invention as claimed in claim 23 wherein thediameter of said one periphery of said annular wear plate is less thanthe diameter of said free annular axially extending portion.
 25. Theinvention as claimed in claim 24 wherein said outer race means isprovided with a portion spaced axially from said annular wear plate butradially overlapping at least a portion of said annular wear plate andsaid resilient annular element includes a portion disposed axiallydirectly between the radially overlapping portions of said wear plateand said outer race means.
 26. The invention as claimed in claim 23wherein the diameter of said one periphery of said annular wear plate isgreater than the diameter of said free annular axially extendingportion.
 27. The invention as claimed in claim 26 wherein said outerrace means is provided with a portion spaced axially from said annularwear plate but radially overlapping at least a portion of said annularwear plate and said resilient annular element includes a portiondisposed axially directly between the radially overlapping portions ofsaid wear plate and said outer race means.
 28. The invention as claimedin claim 23 wherein said free annular axially extending portion isprovided on one end of a cylindrical sleeve whose other end istelescopically engaged with a cylindrical surface of said outer racemeans.
 29. The invention as claimed in claim 28 wherein said outer racemeans includes an end face facing and spaced axially from said annularwear plate, said resilient annular element including a portion disposedaxially directly between said wear plate and said end face.
 30. Theinvention as claimed in claim 23 further including an annular conicalflange extending around the other periphery of said annular wear plate.31. The invention as claimed in claim 30 wherein said annular conicalflange extends around the inner periphery of said annular wear plate.32. The invention as claimed in claim 31 wherein said annular conicalflange tapers radially inwardly in the direction away from said innerrace means.